If you are running Citrix Provisioning Services (PVS) prior to version 7.1 you might be experiencing some issues with your applications.

The issues generally relate to random crashing of Microsoft Office applications or performance issues of those applications. When the applications crash I’ve often seen 0xc0000005 exception codes in the event logs.

When this occurs you will likely find that Provisioning Services (PVS) has the write cache set to target device which is a very common configuration. If you are experiencing similar issues with this configuration you maybe suffering from ASLR and Provisioning Services (PVS) compatibility problems.

ASLR is Address Space Layout Randomisation which is a Microsoft Windows technology that attempts to randomise placement of process data into memory to reduce the processes attack surface. This unfortunately does not place nicely with older versions of Citrix Provisioning Services (PVS) as PVS will modify the memory descriptor location before writing data the the write cache and when the data is reread into memory ASLR triggers the exception.

You can test if this issue is relevent to your environment by either changing the mode of a vDisk to private Image or maintenance mode and trying to reproduce the problem. Another method you could use is to change the cache type something other than target hard disk.

Presuming that you are experiencing issues with Citrix Provisioning Services (PVS) and ASLR the recommended solution is to upgrade the version of Citrix PVS to a minimum of 7.1. This generally ties in nicely with Citrix Provisioning Services (PVS) 6.x going end of maintenance in June 2015 so you should be thinking of upgrading at this point anyway. In addition the more recent versions have beefed up their write cache RAM options which gives massive IOP benefits (Read HERE).

Author: Dale Scriven

 

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